The AD is a nice bike. I was in the bike business form 1974 through 1994 and sold AD in the late 70's and early 80's. FWIW, I don't think your bike is a 1971 model. If the components are original, the oldest it could be is around 1975, and my memory is that this bike is really closer to 1978. Of course, that doesn't make any difference because the bike is a nice example of 70's mid-level road machine, regardless of the actual age.
Have fun with it.
R.